Percussion tool



Aug. 10, 1943. D. L, GARRETT PERCUSS ION TOOL Filed Jan. 24, 1942 2 Sheets-Sheet 1 DAVID L. (BARR ET IN VEN TOR.

Aug. 10, 1943. D. L. GARRETT PERCUSSION TOOL Filed Jan. 24, 1942 2 Sheets-Sheet 2 DAVID L. GARRETT,

9 mm Wm m mm 8 RV Eu T m 2 w b r i i A/ r #IlllliJ H N .m w? WW imm F l||| I \i 1 N7 Tim ow a \.m w? IQ 5 mm H m. N @W UN 9 Patented Aug. 10,1943

omrso STATES PATENT OFFICE I PERCUSSION TOOL David L; Garrett, Denver, 0010. Application January 24, 194.2, Serial No. 428,026

9 Claims.

s invention relates to apparatus of hammer deleted to deliver a rapid succession of blows to and work effect on a tool associated and has asan object to pro cred construction and arrangement or el ments constitutin" such an apparatus.

A 1 they object of the invention is to provide irprc Jed means for actuating a reciprocable impact element for work ffect on a tool.

A further cbiect of the invention is to provide rave-cl arrangement of means operable to m continuous rotary motion into reciproo'ticn of on impact or hammer element. er object of the invention is to provide mproved constru on and arrangement of an electric motor in 'v ng relation with a rcclprocable impact eleurthe;= object of the invention is to provide proved power hammer adapted for operssoc'iuti with variety of specific tool A further object of the inventi .1' is to provide n oved power that is small in size ortion to its power'output, co hpact in relatively light in Weight, simple of conn and opernti' 1 so stantiolly free from so vibratory ch racteristics, positive and c it in use, and available for operation wherctr cwer is obtainable.

inversion consists in the construction, 3.1"- rengement, combination of elements hereinal tel set forth, pointed out in my claims, and illustrated by the accompanying drawings, in

which:

Figure l lly and longitudlnelly through one embodiment of the inveng is a fragmentary, detail section,

1 scale, taken substantially on the 2-2 of Figure l. Figurefiis a cross section, on the same scale as Figure 2, taken substantially on the indicated line 3-3 of Figure 1. l 'igure 4 is longitudinal section taken axially through an alternative embodiment of the invention. Figure 5 is a cross section, on an enlarged scale, taken substantially on the indicated line 5-5 of Figure 4. Figure 6 is a; longitudinal section taken axially through a modified form of the typical hammer shown in figure 4. Figure 7 is a fragmentary, detail section, on an enlarged scale, taken on the indicated line l? of Figure 6.

In the construction of the apparatus us shown in Figures 1-3, inclusive, the numeral l0 designates a rigid, tubular shell or casing formed of any suitable material, such as metal, cylindrical in form, open at each end, and provided with a straight, uniform, cylindrical bore. The shell so is normally closed at one end by means of a cap plate l mounted for removal and replacement to permit access to the corresponding en of the shell, and is closed at its other end by a relatively heavy plug l2 which threadedly, or otherwise, removably and replaceably engages with the shell. A web l3 is disposed transversely of and within the shell I0 between the cap H and the plug l2, thereby dividing the shell interior into two compartments, and the web l3 is disposed more nearly adjacent the cap ll than the plug l2 to provide a larger'of said compartments adjacent said plug. The web I3 is centrally aperture-d and recessed to receive and seat on anti-friction bearing assembly I4 and the inner face of the plug 12 is formed with a central recess wherein is seated an anti-friction bearing assembly 15, said assemblies H and I5 being thus disposed to engage and rotatably support opposite end portions of a. hollow shaft l6 which is the eby mounted to extend longitudinally and axially through the larger compartment of the shell If The shaft [5 functions as the driven shaft of an electric motor and directly carries elements I! constituting the armature and el ments l8 constituting the commutator of a typical motor assembly whereof the field elements P3 are fixedly associated with the shell II! in operative relation with the armature elements ll. The motor elements of the apparatus are illustrated conventionally and may be of any specific type and construction suitable to their purpose, which is to efi'ect rotation of the shaft l5 when electrical energy is supplied thereto. The motor should preferably be characterized by high starting torque, small diameter, and relatively slow speed. such motors being available and Well known. One end of the shaft 15 extends through the web l3 and into the shell compartment between said web and the cap I i, and said end of said shaft is formed as or rigidly secured to a cylindrical cup 28 substantially filling the diameter of the shell and opening toward the can H.

The plug I2 is centrally apertured to provide an opening registering with the bore of the shaft I6, and said plug is formed with an axial, cylindrical, exterior extension 2| which is provided with an end-opening, axial bore somewhat'greater' in diameter than the aperture registering with the shaft bore,-and a bearing sleeve 22' is seated within, extends throughout the length of ing thimble spring 38 surrounds the sleev 22 v and is preferably associated for convenient removal and replacement with the bore of the plug lation with one end of a stem 24 which extends through the shaft IE and cup to terminate adjacent the cap H, said stem 24 preferably being supported near its end remote from the head 23 by abushing or equivalent device carried centrally of the cup 20 and in bearing engagement against said stem. The sleeve 22 is formed with longitudinally-disposed slots 25 opening through portions of the sleeve wall intermediate the sleeve ends, and lugs 26 fixed to and extending radially from the head 23 slidably engage within the slots 25 and hold said head 23 against rotation within the sleeve while accommodating reciprocation of said head axially of the sleeve.

and substantially fills the bore of the sleev 22, thereby providing an annular space within said sleeve and about said stem between the head 23 and the web of the plug H2, in which space is mounted an expansive coil spring 2! disposed to of the-cup 20. It is the function of the cup 2t,

when rotating, to retract the head 23 and stem 24 against the pressure of the spring 21, and for this purpose the circular margin of said cup is contoured to provide a suitable cam track 33 wherewith the rollers 29 engage. The cam track 30 is shown in the drawings as having two diametrically opposed peaks and complementary valleys inimmediate trailing relation therewith, so that each rotation of the cup 20 is productive of two reciprocatory cycles of the impact assembly;

As will be apparent, impact effect deriving from reciprocation of the head 23 and stem 24 may be applied in various ways to the-end of a tool shank suitably received within the open end of the sleeve 22, an arrangement suitable for such purpose being illustrated in association with a riveting head in Figure 1. As illustrated, a tappet block 3| is slidably received in the open-end portion of the bore of the sleeve 22 and therein positioned to receive the blows delivered by the head 23. The outer'end of the block 3| is formed with a threaded socket, or equivalentarrangement, whereby a tool member 32 may be removably and replaceably secured'to the block. Studs 33 project radially from the block 3| and engage through the slots 25 of the sleeve 22, said studs projecting beyond the outer surface of said sleeve for engagement of their outer ends within a ring 36 thereby positioned to slide with the block 3! on and exteriorly of the sleeve 22. An adjust- 37' threadedly engages on and exteriorly of the free end of the sleeve 22 in spaced relation with the ring 35, and an expansive coil in bearing 'engagement between the'ring 36 and thimble 31 to normally urge said ring away from said thimble. A housing sleeve 39 telescopes over and is secured at one end to the thimble 31, said sleeve The head 23 is L or a diameter greater than that of the stem 2 extending across the spring 38 and ring 36 to telescoping engagement of its other end with and about the end of the plug extension 2!, and said sleeve 39 detachably engages and serves to position a ring disposed between the ring 3% and the end of the plug extension 2i, so that an expansive coil spring 4i exteriorly surrounding the sleeve 22 between the rings 35 and 5| acts to balance the pressure of the spring 38 and yieldably position the tappet block 3| for limited reciprocation axially of the sleev 22. The tappet block 3! and tool carried thereby is thus provided with a cushioned mounting, so that impact effects and consequent vibrations are not transmitted in their full magnitude to other elements of the apparatus, and the tappet mounting also provides for adjustment, through rotation of the threaded thimble 31, in the position of the block 31 within thesleeve 22 for variation of the maximum spacing between said block and the impact head 23, with consequent variation in the travel of said head prior to impact and corresponding control of the force of the blow delivered.

One or more handles 42 may be associated with the shell l9 and positioned as desired for convenience in holding and manipulating the apparatus and a switch trigger 3 may conveniently be associated with a handle 42 for control of current supply to the motor elements of the assembly.

The embodiment of the apparatus shown in Figures 4 and 5 is the same in operative principle as that hereabove described and difiers principally in that the reciprocatory assembly is mounted for rotation with the motor shaft it While the cup carrying the cam track 38 is held stationary. In the alternative embodiment, the shell Hi, cap ll, plug i2, web it, bearing assemblies i4 and i5, hollow shaft 15, and motor ele ments ll, 58 and 19, are functionally and structurally substantially the same as shown in Figure 1 and above described. Instead of the cup 20 carried by and for rotation Withthe shaft IS, the web i3 is provided with a concentric, annular cup extension as directed toward the cap l I, the annular margin of said extension being formed to provide the desired cam track 3%. The motor shaft l6 has an axial bore suiiicient in size to receive and slidably accommodate an impact head 23 which is mounted to rotate with said shaft,

and reciprocate relative thereto by means of rollers, or equivalent devices 44 carried by the inner ends of studs fixed in circumferentially spaced relation radially of said shaft, the head 23' being formed with longitudinal slots or splines Wherein said rollers 44 engage. A stem 24, of less diameter than the head 23', fixedly engages the end of said head adjacent the web is and extends axially of the shaft it through a hole in the web 13 and through a bearing in the cap it, so that said stem is supported and guided for rotation and reciprocation. A housing cap it removably and replaceably engages the cap H in covering relation with the otherwise exposed end of the stem 26' and the bearing, supporting said stem. A cross-head '28 is fixed to and for rotation with the stem 24' between the cam track 36 and the cap l l, and said cross-headis provided with roll ers 29 adjacent its outer ends and positioned for rolling engagement against the cam track 3i! when the stem 2 is caused to rotate. The head 23' is normally urged toward the plug l2 and into engagement of the rollers 29 against the cam track 30 by means of an expansive coil spring 41 which surrounds the stem 24 within theshaft aaaarae l6 and acts between the shoulder of the head 23" and the web it, an anti-friction bearing as sembly 43 preferably being interposed between the web l3 and the adjacent end or the spring 4'! to facilitate rotation of said spring relative to said Web. With the arrangement shown and described-activation of the motor results inrotation of the shaft l5, head 23', stem 24", and cross-head 28 carrying the rollers 29', s that said rollers 29 are caused totraverse the cam track 30' with consequent retraction of the head 23' against the pressure of the spring 41 until the peaks of the cam track have been passed, whereafter' said spring acts to drive the head 23' axially within the shaft Hi and toward the plug n.

In the construction according to Figured, the blows of the head 13 are receivedon theinner end of a cylindrical plug or tappet 49 which engages at its inner end through a bearing formed centrally of the plug '2 and extends within the bore er. the shaft It; The tappet 49-15 loosely hcused Within a sleeve so which threadedly' engages at its inner end with an interiorly-threaded boss 51 projecting axially from the plug [2, and the outer endof the tappet 49 is slidably received in and supported by athimble 52' which threads into the outer end of the sleeve '59. An annular rib 53 is formed onand projects circumferentially from the tappet 48 within the sleeve 50 and between the end of the thimble 52 and the web of the plug l2, so-thatexpansive coil springs 54 and 55, surrounding the tappet 09 on opposite sides of the rib 53, may function to yieldably position said tappet 49 while permitting travel of said tappet under the influence of impacts driving from-the head 23 The outer end portion of the thimble 5211s formed to receive. and guide the end of a tool. shank, such: asa hexagonal ba-r 56, and atool retainer of conventional type, indica'ted at 57 may be engaged with the outer end of the thimble 52. to.- prevent accidental separation of the tool 58 from said thimbler The structural and operative. relation; of the elements constituting the apparatus illustrated in Figure 6 is closely similar to that. shown in FigureA, and differs from: said latter figure chiefly in that the showing of Sincludesmeans for rotating the-tool acted upon by the apparatus, means for feeding fluictto and. through the tool 1 shank, and. convenient. means for: adjusting the effective pressure of. the spring acting to drive the impact head. T provide. means for rotating the tool. shank,. the: plug I22 is replaced by a web lzxwhich carries the bearing assembly IS in supporting relation: with. oneiend of: the. hollow shaft. 15. and which. is centrally. apertured. to: accommodate an end. extension of said shaft I'B which carries a hollow gear 58'. The shell I0 is extended. for a distance beyond the web- I2 to provide an end compartment which is closed by the removable cap 59 formed with a -central aper ture defined and. lengthenedby meansof an exteriorly-projecting annular flangezifl. A gear 6!,

larger in diameter than the gear 58, is formed on or fixed to theinner. end of a sleeve 62 which engages through and is mounted for rotation in the flange 60 and central aperture in the cap 59, said gear 6| being thus disposed in parallel, ad-

jacent relation with the gear 58. A plurality of units, having each a larger pinion 63 and a smaller pinion 64 connected for simultaneous rotation in adjacent, parallel relation, are mounted for rotation on shafts 65 engaging between the web I! and cap 59 in parallel relation with the axis of the shaft I6; and said unitsar'e disposed with their larger gears 53 meshing with the gear 58 and their smaller gears meshing with the gear Gi so that rotation of the shaft l5 operates through the meshed gears to rotate the sleeve 62 in the same direction as and ata speed less than that of said shaft 15. The outer end of the sleeve 52 extends beyond the end margin of the flange and detachably engages with a tool retainer ST in such manner. as to hold the gear 51 against a thrust ring bearing on the inner face of the cap- 50, thereby holding the sleeve '81 and gear lil against and play. The sleeve- 52' and gear 6| are formed with an axialbore angular in cross section and adapted to slid'ably receive the corresponding angular end of atool' shank 55, so that rotation of said sleeve and gear transmitted' to and for rotation of the tool shank engaged therethrought 1 Means for the convenient manual v adjustment of the pressure exerted by the spring n on the head 23" is shown as: comprising a follower ring or abutment 66. slidably mounted on the stem 24' within the end' of the shaft lladjacent the web. l3 inpositi'on to bear'against the-corresponding endof. the spring: 11, a plurality of thrust rods 61 in parallel. relation with and exteriorly of the stem. 24" and rigidly connecting the abutments 56' with a slide ringv 58 mn'va'ble on the stem- 24" Within a cylindricalbore formed; centrally oi the cap H, and an anti-friction thrust bearing assembly 69 operatively engaging the face of the slide ring 68 remote: from thea-butm'enc 66; The rods 51 preferably pass slidably through the hub of the cross-head. 28 and are accommodated for'free rotation in a central aperture at the web l3. The cap II is formed with an axiallgerterior boss 10 which'is'recessed toiproviide the 'mwardlyopening bore wherein theslide ring as and hearing 69. are housed, and: the boss. 7 0 is apertured centrally of its outer end to threadedly receive a sleeve H; which: telescopes; over and rotatably receivesthe end of the' stemfl' and beans at its inner end against. the: bearing: assembly 69 so that rotation of the sleeve 'l-I' acts through its threadedengagementrwitfh the: end of the boss 10 to shift the abutment longitudinally along the stem 24 for consequent contractibn or expansion of the spring 41 and variation. of the pressure exerted by said spring; A handwheel 12; or similar device, may be fixed to the. portionof the v sleeve H: projecting beyond the boss W for convenience-in rotating the sleeve Ila.

In the operation of certain tools, such as rock drills, it is of. advantage to introduce water to the face of the tool, as is common practice; and the construction. shown. in. Figure 6' is adapted for this purpose. The tool shank 55 shown in the drawings is provided: with anaxial. bore or channel 13;. such as is commonly provided in drills. of certain types; and the impact head 23' and stem 24' are similarlyprovided with an axial adjacent the tool shank 56' is formed to telescope over and? slidabl y receive the end of a tube 15 which extends within and is frlctionally held by the bore 13 ofthe-'tool-shanlt, so t'hat a continuous flow passage is provided from the bore 14, through the tube 15 and to the bore 13 of the tool. The end of the stem 24' which reciprocates H is preferably worked to receive washers or packing material 16 which oper- 'oints between said stem and thimble against leakage of water therethrough,

. illustrative showing and foregoing description.

I claim as my invention- 7 1. A percussion tool comprising, an electric motor having a hollow driven shaft, an impact assembly reciprocable axially of said shaft, spring means normally and yieldably urgingsaid impact assembly outwardly of saidshaft in one direction, and cam means engaging with said impact assemblyand operable as an incident of motor shaft rotation to intermittently retract said assembly against the pressure of said spring.

2. A percussion tool comprising, a housing, an

electric motor field assembly fixedly carried by said housing, an electric motor armature assembly rotatably carried by said :housing in operative association with said field assembly,.a bore axially through the driven shaft of said armature assembly, an impact assembly reciprocably associated with said bore, spring means yieldably urging said impact assembly in one direction outwardly of said bore, and can'rmeans engaging said impact assembly and operable as an incident of armature shaft rotation to intermittently retract said impact assembly against the pressure of said spring.

3. In a percussion tool, ing a hollowdriven shaft, an impact assembly reciprocable axially of and held against rotation Within said shaft, spring means normally and yieldably urging said impact assembly outwardly an electric motor hav of said shaft in one direction, and cam means 7 rotatable with said shaft .in engagement with said impact assembly to intermittently retract said assembly against the'pressure of said spring.

4. In a percussion tool, an electric motor having a hollow driven shaft, an impact assembly reciprocable axially of and rotatable within said shaft, spring means normally and yieldably urging said impact assembly outwardly of said shaft in one direction, and cam means held against ro-.

tation in engagement with said impact assembly to intermittently retract said assembly against the pressureof said spring. as an incident of shaft rotation. V a

15. In a percussion tool havingan electric motor formed with a hollow driven shaft, an impact assembly comprising a head and fixedly-associated stem coaxial within and reciprocable relative to said shaft, spring means yieldably urging said impact assembly "toward one limit of its range of reciprocation, a cross-head on the impact assembly stem exteriorly of said shaft, and a cam track in engagement with said cross-head and operable as an incident of shaft rotation to intermittently retract the impact assembly against the pressure of said spring.

6.. In a percussion tool having an electric motor formed with a hollow driven shaft, a stem coaxial-within and reciprocable relative to said shaft, an impact head on one end of said stem, a cross-head on the other end of said stem exteriorly of said shaft, spring means yieldably urging saidimpact head outwardly of said shaft, a resiliently-positioned tappet in axial alignment with said impact head and for engagement therewith at an outer limit of the range of impact head travel, means for operatively' associating a tool with the end of said tappet remote from said impact 7 head, and cam means engaging said cross-head for intermittent retraction of the impact assembly against the pressure of said spring.

7. In a percussion tool having an electric motor formed with a hollow driven shaft, an impact assembly comprising a head and fixedly-associated stem coaxial within and reciprocable relative to said shaft, means slidably engaging between said impact assembly and shaft for rotation of the former with the latter, spring means yieldably urging said impact assembly toward one limit of its range of reciprocation, a cross-head fixed to the impactassembly stem exteriorly of said shaft, and a fixed cam track in engagement with said cross-head operable as an incident of shaft rotation to retract the impact assembly against the pressure of said spring.

8. In a percussion tool having an electric motor formed with a hollow driven shaft, an impact assembly comprising a headand fixedly-associated stem coaxial within and reciprocable relative to said shaft, means slidably engaging'said impact assembly to hold said assembly-against rotation with said shaft, spring means yieldably urging said impact assembly toward one limit of its range of reciprocation, a cross-head fixed to the impact assembly stem exteriorly of said shaft, and a cam track rotatable with said shaft in engagement with said cross-head and operable as an incident of such rotation to retract the impact assembly against the, pressure of said spring.

9. In a percussion tool having a housing, an electric motor operatively and coaxially within .said housing, and ahollow driven shaft in said motor, an impact assembly coaxially within, re-

ciprocable relative to, and extending at each end beyond said shaft, animpact head on one end of said assembly, a cross-head fixed tothe other end of saidassembly, spring means normally urging the head end of said assembly to thelimit of its extension relative to said shaft, cam means engaging said cross-head and operable as'an incident of shaft rotation to intermittently retract said assembly against the pressure of said spring, a tappet reciprocably carried by said housing in axial alignment with said impact assembly adjacent and in position to be engaged by the head of :saidassembly, means for associating a tool shank in engagement with the end of said tappet remote from said head, and spring means engaging between said tappet and housing to. resiliently and adjustably position said tappet.

DAvrD L. GARRETT. 

